Corrected entry: One crucial piece in Poirot's puzzle is the bathing cap that Christine reminds Linda to wear, so that she can't hear the noon-day gun, but there is no way such a thin rubber cap could be sufficiently sound-proof. (01:30:05)
NancyFelix
27th Apr 2004
Correction: Actually it would stop the noise or at least muffle it enough that her splashing would cover the shot. Try it.